Schematic diagram
When the conductive fluid flows through a magnetic field perpendicular to the flow direction, the conductive fluid induces an induced voltage E proportional to the average flow rate. The induced voltage is detected by two electrodes in direct contact with the fluid, amplified, filtered and shaped by the converter and then sent to the single chip microcomputer to complete the display and output control of instantaneous flow and accumulated flow. E=KBVD where: E-induced voltage? K-instrument constant B-magnetic induction intensity V-average flow velocity on the surface of measuring tube D-flowmeter diameter.
Product structure diagram
A good electromagnetic flowmeter has high measurement accuracy and stable product performance. At present, the accuracy of electromagnetic flowmeter is generally 0.3 and 0.5, and some small-caliber products can achieve 0.2. Because of the particularity of its measuring principle, it is necessary to measure the medium with a certain conductivity (generally greater than 5us/cm), and there are also certain requirements for measuring the initial flow (generally greater than 0.5m/s).
TSD electromagnetic flowmeter has many advantages in fluid flow and is widely used in various industries at present.
(1) There is no obstruction and pressure loss caused by over-current parts in the measuring pipe, so the requirements for straight pipe section are relatively low;
(2) High measurement accuracy, strong stability and strong anti-vibration interference ability;
(3) The measurement is not affected by the changes of fluid density, viscosity, temperature, pressure and conductivity;
(4) It has a variety of electrode and lining choices, and has strong medium corrosion resistance.
(5) The range ratio is large, which is generally 10: 1 at the flow rate of 0.5-5m/s, and it can be 100: 1 even 150: 1 at some caliber and flow rates.
Of course, electromagnetic flowmeter also has its unique limitations:
(1) The measuring medium must have a certain conductivity (generally greater than 5us/cm), and there are certain requirements for measuring the initial flow (generally greater than 0.5m/s).
(2) The temperature of measuring medium is limited by the lining material, and the measuring effect on high-temperature medium is not good.
(3) Gas, steam and other media cannot be measured.
(4) Scaling may occur when the measuring electrode works for a long time, and it can only be measured after cleaning.
(5) For highly viscous medium and solid-liquid two-phase medium, high-frequency excitation is needed, and low-frequency weak magnetic precision is poor.
(6) Due to the limitation of sensor structure principle, the cost of large-caliber products is too high, which leads to the increase of product caliber and the soaring price.
(7) Due to its principle limitation, the instrument induction coil needs to be electrified to generate a magnetic field, which has high power consumption and is not suitable for battery power supply.
Despite the above shortcomings, electromagnetic flowmeter is still widely used in the measurement of most liquid media, and its excellent measurement accuracy and low maintenance cost are deeply loved by customers.
To sum up, electromagnetic flowmeters have their own advantages and disadvantages. Users should choose suitable flowmeter products according to industry and working conditions.